<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script>
    function fun(n, o) {
        console.log(o)
        return {
            fun: function (m) {
                return fun(m, n)
            }
        }
    }
    var c = fun(0).fun(1);

    c.fun(2);
    
    c.fun(3);

</script>
</html>